Ink jet printer including external deflection field

Abstract

An ink jet printer for depositing drops at print positions on the surface of a print receiving medium includes a print head means for generating a plurality of jet drop streams directed toward the print receiving medium, each drop in the jet drop streams being charged to one of a plurality of charge levels. A deflection means generates a static electrical deflection field extending through the print receiving medium in a direction non-parallel to the plurality of jet drop streams for deflecting charged drops in the streams to print positions on the print receiving medium. In a first embodiment, the deflection means includes a deflection electrode plate which is nonperpendicular with respect to the jet drop streams. In a second embodiment, a deflection electrode of bulk resistive material is provided.

What is claimed is: 
     
       1. An ink jet printer for depositing drops at print positions on the surface of a print receiving medium, comprising: print head means for generating a plurality of jet drop streams directed toward said print receiving medium, each drop in said jet drop streams being charged to one of a plurality of charge levels, and   deflection means for generating a static electrical deflection field extending through said print receiving medium in a direction nonparallel to said plurality of jet drop streams for deflecting charged drops in said streams to print positions on said print receiving medium.   
     
     
       2. The ink jet printer of claim 1 in which said print head means comprises catcher means for receiving drops in said jet drop streams which are not to be deposited on said surface of said print receiving medium, and   electrode means for providing an electrical deflection field to deflect drops in said jet drop streams, thereby separating said drops into catch trajectories in which said drops strike said catcher means and print trajectories in which said drops are directed towards said print receiving medium.   
     
     
       3. The ink jet printer of claim 1 in which said plurality of jet drop streams are parallel and arranged in a row. 
     
     
       4. The ink jet printer of claim 3 in which said deflection electrode means comprises a first deflection electrode of bulk resistive material, positioned on the side of said print receiving medium opposite said print head means, and means for supplying an electrical deflection potential, connected to opposite ends of said deflection electrode, to induce current flow therethrough in a direction substantially parallel to said row of jet drop streams to produce said deflection field. 
     
     
       5. The ink jet printer of claim 4 in which said print head means further comprises a second electrode of bulk resistive material having a plurality of orifices through which associated jet drop streams pass, said second electrode having opposite ends connected to said means for supplying an electrical deflection potential, to induce current flow therethrough in a direction substantially parallel to said row of jet drop streams to supplement the deflection field provided by said first deflection electrode. 
     
     
       6. The ink jet printer of claim 3 in which said deflection means comprises deflection electrode means, positioned on the side of said print receiving medium opposite said print head means, and   means for applying an electrical deflection potential to said deflection electrode means.   
     
     
       7. The ink jet printer of claim 6 in which said jet drop streams are directed toward said print receiving medium in a direction nonperpendicular to said surface of said print receiving medium, and in which said means for applying an electrical deflection potential to said deflection electrode means comprises means for supplying an electrical potential between said print head means and said deflection electrode means to produce a deflection field extending through said print receiving medium in a direction substantially perpendicular to said surface of said print receiving medium. 
     
     
       8. The ink jet printer of claim 7 in which said deflection electrode means comprises an electrically conductive electrode plate positioned adjacent said print receiving medium and substantially parallel to said surface of said print receiving medium. 
     
     
       9. An ink jet printer for depositing drops on the surface of a print receiving medium to form a print image thereon, comprising: means for transporting a print receiving medium past a print station,   means for generating a plurality of parallel jet drop streams directed toward said print receiving medium at said print station in a direction nonperpendicular with respect to said surface of said print receiving medium, and   deflection means for providing a deflection field extending in a direction substantially perpendicular to said surface of said medium, whereby drops in said drop streams pass through and are deflected by said field to strike said medium at a plurality of print positions, thereby collectively forming said print image.   
     
     
       10. The ink jet printer of claim 9 in which said jet drop streams are arranged in a row substantially perpendicular to the direction of movement of said print receiving medium. 
     
     
       11. The ink jet printer of claim 9 in which each of the drops in said plurality of jet drop streams is charged selectively to one of a plurality of charge levels and in which said deflection means includes means for providing a static electrical deflection field. 
     
     
       12. The ink jet printer of claim 11 in which said means for providing a static electrical deflection field comprises electrode means, positioned adjacent said print receiving medium, and   means for providing an electrical potential differential between said electrode means and said print head means.   
     
     
       13. An ink jet printer, comprising: means for transporting a print receiving medium past a print station,   print head means for generating a row of substantially parallel jet drop streams directed at a print receiving surface of said print receiving medium, and   deflection electrode means positioned on the side of said print receiving medium opposite said print head means for producing a static electrical field having a field component in a direction parallel to said row for deflecting charged drops parallel to said row to a plurality of print positions on said print receiving medium.   
     
     
       14. The ink jet printer of claim 13, in which each drop in said jet drop streams is charged to one of a plurality of charge levels. 
     
     
       15. The ink jet printer of claim 13 in which said print head means comprises catcher means for receiving drops in said jet drop streams which are not to be deposited on said surface of said print receiving medium, and   electrode means for providing an electrical deflection field to deflect drops in said jet drop streams, thereby separating said drops into catch trajectories in which said drops strike said catcher means and print trajectories in which said drops are directed towards said print receiving medium.   
     
     
       16. The ink jet printer of claim 13 in which said deflection electrode means comprises a first deflection electrode of bulk resistive material, positioned on the side of said print receiving medium opposite said print head means, and means for supplying an electrical deflection potential, connected to opposite ends of said deflection electrode to induce current flow therethrough in a direction substantially parallel to said row of jet drop streams to produce said deflection field. 
     
     
       17. The ink jet printer of claim 16 in which said print head means further comprises a second electrode of bulk resistive material having a plurality of orifices through which associated jet drop streams pass, said second electrode having opposite ends connected to said means for supplying an electrical deflection potential, to induce current flow therethrough in a direction substantially parallel to said row of jet drop streams to supplement the deflection field provided by said first deflection electrode. 
     
     
       18. The ink jet printer of claim 13 in which said deflection means comprises deflection electrode, positioned on the side of said print receiving medium opposite said print head means, and   means for applying an electrical deflection potential to said deflection electrode.   
     
     
       19. The ink jet printer of claim 18 in which said jet drop streams are directed toward said print receiving medium in a direction nonperpendicular to said surface of said print receiving medium, and in which said means for applying an electrical deflection potential to said deflection electrode means comprises means for supplying an electrical potential between said print head means and said deflection electrode means. 
     
     
       20. The ink jet printer of claim 19 in which said deflection electrode means comprises an electrically conductive electrode plate positioned adjacent said print receiving medium and substantially parallel to said surface of said print receiving medium.